#include <iostream>
#include <tf/transform_datatypes.h>

int main()
{
    double a = -1.93126, b = -6.79717, c = -1.8823, d = -6.80498;
    double dx = a - c, dy = b - d;
    tf::Vector3 v1(a, b, 0), v2(c, d, 0);
    std::cout << (v1-v2).length() << "\n";

}